1. Field of the Invention
The present invention relates to a liquid crystal display in which glare on a display screen is reduced, and a surface light source device.
2. Description of the Related Art
In liquid crystal displays, when the display screens produce glare, image quality is deteriorated, and thus it is desired that the glare on the screens is reduced. Techniques for suppressing the glare on the screens in the liquid crystal displays have been proposed for example, in Japanese Patent Application Laid-Open Nos. 2002-107706 and 11-352312 (1999).
In a liquid crystal display described in Japanese Patent Application Laid-Open No. 2002-107706, the following method is proposed. According to this method, a diffusion layer and a glare-proof layer, provided on a front surface of a liquid crystal panel, diffuses light emitted from the liquid crystal panel, and the total haze value is set to 30 to 80%, so that the glare on the screen is made to be unnoticeable.
In the liquid crystal display described in Japanese Patent Application Laid-Open No. 2002-107706, however, since the light emitted from the liquid crystal panel is diffused, definition of an image is deteriorated and front surface luminance (in this specification, the forward direction of the liquid crystal display is occasionally called the front surface) is deteriorated.
In a liquid crystal display described in Japanese Patent Application Laid-Open No. 11-352312 (1999), a rough plane is formed on a light-emitting plane of a light guide plate, and the light emitted from the light-emitting plane is diffused on the rough plane so that the glare on a screen is made to be unnoticeable. Thereafter, a prism sheet deflects scattering light in a direction approximately vertical to the light-emitting plane.
In the liquid crystal display described in Japanese Patent Application Laid-Open No. 11-352312 (1999), since the scattering light is aligned to the direction vertical to the light-emitting plane by the prism sheet, a decrease in the front surface luminance of the liquid crystal display can be suppressed. Due to the rough plane formed on the light-emitting plane, however, the definition of an image is deteriorated, and the decrease in the front surface luminance caused by the rough plane cannot be completely recovered by the prism sheet. In the liquid crystal display described in Japanese Patent Application Laid-Open No. 11-352312 (1999), since the prism sheet is expensive, this prevents price-reduction of the liquid crystal display.
In the above related art, the glare on the screens is reduced only according to response measures, and the cause of the glare is not clarified and thus the there is still glare on the screen.